<!DOCTYPE html>
<html>
<head>
<script src="../../resources/js-test.js"></script>
<script>
function test() {
    iframe = document.querySelector('iframe');
    shouldBeTrue('iframe instanceof HTMLIFrameElement');
    shouldBeFalse('iframe instanceof iframe.contentWindow.HTMLIFrameElement');
    finishJSTest();
}
description("Accessing window.frameElement from inside an iframe should not cause the &lt;iframe&gt;'s prototype to come from its own context.");
window.jsTestIsAsync = true;
</script>
</head>
<iframe onload="test();" srcdoc="
<script>
window.frameElement;
</script>
"></iframe>
</body>
</html>
